To a solution of ethylvinylether (5.8 ml, 60 mmol) in dry THF (50 ml) at −78° C. was added t-BuLi (1.7 M in pentane, 25 ml, 40 mmol) and the yellow mixture was stirred for 1 h at −78° C. The cooling bath was removed and the mixture was warmed slowly to 0° C. and stirred for another 30 min. The mixture was recooled to −78° C. and a solution of ZnCl2 (2M in THF, 20 ml, 40 mmol) was added slowly and the cooling bath was removed and varmed to 20° C. 5-Iodo-2-aminobenzenesulfonamide (see compound 37) (1.8 g, 6 mmol) and Pd(PPh3)4 (0.2 g, 3 mol %) was added and the mixture was refluxed for 6 h. The THF was evaporated and the residue was boiled in 1 M hydrochloric acid (30 ml) and MeOH (30 ml) for 30 min. EDTA (14.6 g, 50 mmol) was added and made slightly basic (pH≈8–9) with 1 M NaOH followed by extraction with EtOAc (3×150 ml), drying (Na2SO4) and evaporation of the solvent gave a brown solid. Trituration with n-hexane gave 0.95 g (74%) of 5-acetyl-2-aminobenzenesulfonamide as off-white powder. The product was further transformed by Method G (using cyclohexanecarboxaldehyde). M.p. 224–226° C. (decomp).
